We still do not know if annual flu shots do more good than harm
In spite of all of the observational studies reporting "vaccine effectiveness" we still do not know if annual flu shots have done more overall good than harm--for the general public, for high risk groups, or for health-care workers. Some studies have shown that flu shots and the nasal vaccines have sometimes INCREASED the risk of influenza and other viral respiratory infections. We need the long-term, multicenter, randomized trials suggested by Kenneth McIntosh in a 2000 NEJM editorial, but never carried out. It is possible that annual flu shots has reduced our collective immunity and increased our risks for when the "Big One" next appears.
ALLAN s. CUNNINGHAM 10 June 2019
Competing interests: No competing interests